Here is the full list of all 25 Bogatyr achievements.
Complete the game with 1st ending
Complete the game with 2nd ending
Pick up the axe
Kill all the ghouls in the Fortress
Pass to Swamps through Dense Forest
Kill the Three-Headed Snake God
Present the Pearl to Three-Headed Snake
Find out what happened to your squad
Learn about your family fate
Eat poisonous mushroom
Negotiate with the ghoul successfully
Help Warriors to rebuild the fortress
Kill Egor & Oleg
Support the Snake Cult
Support the Decomposition Cult
Talk to the mongol
Serve water to old woman in Zhmenki village
Plunder Svyatovidsk village Elder
Seduce well mermaids being intoxicated
Get the Poleaxe
Destroy every single one Snake Totem
Destroy any ghoul spawner
Herd Emelyan's sheep back to the corral
Kill any domesticated Animal
End the Education Block